(i) Field of the Invention
This invention relates to a meter for measuring the rate at which erythrocytes settle.
(ii) Description of the Prior Art
Measurement of erythrocyte settling rates, usually described as a blood test, is one of the most common medical tests made. When pathogens are present, extra antibodies are secreted and carried in the blood. These are mainly proteins and they cause clumping of red blood cells into rouleaux which are larger than normal and hence settle faster. A blood test shows this, but such test, as presently operated, usually requires two hours for reliable results. In one standard form of blood test, a specific amount of anticoagulant must be used (to prevent clotting during the test) and, to ensure good mixing, a few minutes of shaking of the blood sample is required. Then a sample must be placed in a vertical rack, a timer set and the rate of sedimentation (about 3 mm/hour for healthy humans) observed for one to two hours. Usually the operation is done in a hospital or clinical laboratory. This generally means that, with transportation delays, the results may not be known until the next day.
Other patented proposals have been made in similar and other fields to determine settling rates for solids, or cloud points of liquids or viscosity of liquids.
In the field of blood test machines, German Pat. No. 916,128 dated July 8, 1949 to J. Reppisch provided a blood test machine in which tubes containing blood were held in an incined position, and in which the settling rate was estimated visually by looking straight down into the frame and the sides of the Westergren pipettes used.
U.S. Pat. No. 2,514,260 issued July 4, 1950 to M. S. Rosen provided apparatus for determining the rate of sedimentation of the solid particles in a fluid menstruum, e.g., the erythrocyte sedimentation rate, of any blood-containing sample. The apparatus included a container comprising two parallel circular discs connected at their peripheries by a cylindrical band. The container, when filled with blood, must be maintained vertical. A circular opening was located at one point on the band and a short tube was connected with the opening to facilitate filling of the space between the discs and the band. One face of the disc had indices thereon, to permit reading of volumes of sediment settling within the container.
U.S. Pat. No. 2,528,704 issued Nov. 7, 1950 to P. M. Neuda provided apparatus for determination of the settling rate of erythrocytes. The erythrocyte settling container was of predetermined triangular vertical section which gradually widens from its top to the bottom. The container was disposed so that there was a vertical orientation so that a wide zone of separation of the fluid-solid mixture was provided at the bottom while, simultaneously, both a quick transfer of the plasma through narrowing spaces toward the surface and a subsequent speed sedimentation of the erythrocytes through spaces widening towards the bottom was secured.
U.S. Pat. No. 3,009,352 issued Nov. 21, 1961 to P. M. Neuda provided an improvement in the Neuda triangle of U.S. Pat. No. 2,528,704. The new triangular container was a triangularly shaped flat container, the sides of the triangular being equilateral, with a top aperture, a V-shaped neck outside the triangle, with each side of the V being exactly parallel to the side of the triangle opposite thereof, and a precise scale, on the outside of the triangular container calibrated in desired units.
German Offenlegungsschrift No. 23 24 015 published Nov. 28, 1974 provided a system for measuring the settling speed of erythrocytes in blood by resonant frequency measurement.
Sokal, German Offenlegungsschrift No. 23 41 403 published Feb. 27, 1975 provided a sedimentation test reaction measuring instrument which had a holder for the measuring tube containing the blood. The instrument also had a recording facility. One light source was located at one side of the measuring tube and light beams were transmitted through part of the full length of the measuring tube. On the other side of the measuring tube was arranged a secondary facility which was exposed to light beams. The portion of the light-dark threshold between the blood serum level and the blood corpuscles was recorded. The light source had a grid of horizontal lines and the line elements were at right angles to the vertically positioned measuring tube. The recording facility contained a light sensitive recording strip.
U.S. Pat. No. 3,952,579 patented Apr. 27, 1976 to M. Nakajima provided an improvement in a device for measuring blood sedimentation rates automatically. A light-sensitive paper sheet was disposed so as to be movable relative to a blood sedimentation measuring tube, such as a Westergren tube. A slit was provided between the light-sensitive paper and the measuring tube. Lamp means were provided on one side of the measuring tube opposite to the slit. Thus the shade of the sedimented red blood corpuscles in the measuring tube formed as the light pulsed from the lamp means passing through the measuring tube was projected on the light-sensitive paper through the slit, with the feed of the paper and light pulses occurring in exact synchronism. The rate of the blood sedimentation could be automatically recorded on the paper.
U.S. Pat. No. 4,027,971 patented June 7, 1977 by P. Kolman et al provided an analytical apparatus for counting the quantity of blood fractions. White light, which was directly transmitted through a predetermined volume of the blood, was filtered through a light filter, and light of the selected optical wavelength was passed through.
Heinlein, German Offenlegungsschrift No. 26 31 291 published Jan. 19, 1978 provided a device for the measurement of blood corpuscle sedimentation which had light flux falling on a transducer and enabled its charge to be displayed. A light source and photoelectric transducer were so placed on both sides of a vertical capillary that light flux passed through the capillary and fell on the transducer. An evaluating device was connected to the transducer output, which displayed instantaneous light flux received by the transducer and/or its charge in time.
U.S. Pat. No. 4,187,462 patented Feb. 5, 1980 by R. Haker et al provided a device for determining the blood sedimentation rate in a substantially vertical test tube. The electrical or magnetic property of a given volume of liquid, which was changed by the settling of the erythrocytes in the test tube, was measured as a function of time, by electrical means.
In the more general field of particle rate settling, U.S. Pat. No. 2,379,158 issued June 26, 1945 to P. R. Kalischer et al provided a technique for the determination of the characteristics of the particles in a powdered material using an apparatus including a vertically disposed settling column, a light source and a light sensitive device disposed about the settling column to indicate the relative light transmission through a transparent cross-sectional portion of the column. The light source and light sensitive device were disposed at a sufficient distance from the admission end of the column so that the admitted particles of the powdered material, under the influence of settling forces, underwent a relative gradation resulting in closely similar sized particles being present in any cross-sectional volume of dispersing medium in the settling column when the particles settle past the portion through which light from the light source passed.
U.S. Pat. No. 2,741,913 issued Apr. 17, 1956 to N. Dovau related to racks for holding ungraduated sedimentation tubes against a graduated background. The patented rack was for holding sedimentation tubes beside graduated scales and included a body block member having bottom feet and a central portion supported by and bridging such feet, a front face and a plurality of spaced vertically oriented sedimentation tube openings adjacent the front face. A plurality of spaced graduated scales were provided on the front face adjacent the openings, and a plurality of spring clips were secured to the body block member and were disposed in the openings removably to hold sedimentation tubes therein.
Canadian Pat. No. 912,849 issued Aug. 10, 1972 to P. Cahour et al provided a device for controlling the rate of settlement of a solid in suspension in a liquid involving the use of a settlement cell comprising a vertical, transparent glass column, and a projector for projecting a horizontal beam of light through the column to be picked up by a photoelectric cell which could produce a signal that detected the precise moment when the settling face moved past that level.
U.S. Pat. No. 3,812,966 issued May 28, 1979 to W. A. Beach et al provided a determination of the settling rate of particulate matter by passing a mixture of the fluid and the particulate matter through an inclined tube at a known flow rate within the laminar flow range. Lights were positioned on one side of the inclined tube, and photocells were positioned on the other side. The signals generated thereby could be used to control the operation of a separator.
U.S. Pat. No. 4,182,161 patented Jan. 8, 1980 by W. Greenfield provided a device for automatically timing and recording the sedimentation rate of fluid samples contained in cylindrical transparent test tubes. The device included a rectangular rack having flat vertical walls formed with cylindrical bars for receiving the test tubes, and vertical channels at outer sides of the walls for receiving photographic strips. A lamp inside the rack shone through test tubes to the strips to record the amount of sedimentation of the fluid.
In the realm of non-analogous art, Canadian Pat. No. 715,290 issued Oct. 10, 1965 to P. G. Holdbourne, provided a method for continuously monitoring the cloud point or the pour point of hydrocarbon oil, involving the use of a beam of light which was directed through the oil onto a reflecting surface. The temperature of the oil was measured when the intensity of the beam of light reflected from the reflecting surface decreased a predetermined amount.
U.S. Pat. No. 3,411,352 issued Apr. 29, 1969 to L. A. Hughes provided a colorimeter which included a plurality of photoelectric cells, each having associated with it a light filter which removed all except the particular monochromatic band of light to which the photoelectric cell was primarily responsive and where its peak response was located. Thus, a different cell was used for each colour of light. A receptacle received a colorimeter cuvette containing a specimen, a spring in the cuvette urging it against one side thereof. At one side of the receptacle was an electric lamp as a light source and on the diametrically opposite side, against which the cuvette was urged, were a plurality of vertically displaced photoelectric cells. Each cell had maximum sensitivity to a different monochromatic light and had associated with it a filter for transmitting to the cell that monochromatic light to which its cell had maximum sensitivity. An electric circuit included the lamp, switch means for placing each cell in the circuit, only one at any time, a bridge circuit responsive to the current of the cell then in the circuit, and an electrical heater which operated as an incubator having a plurality of cuvette receptacles. A plurality of interchangeable meters, each relevant to one particular test and calibrated for direct reading in that test in conjunction with one cell and each insertable into and removable from the electric circuit was supplied, but only one was used at a time across the bridge circuit for measuring light transmissivity of the specimen as expressed by the current passing through the photoelectric cell then in the electric circuit. Some of these meters had an actuator and some did not, the actuator, when present, throwing the switch means to place a different cell in the electric circuit.
U.S. Pat. No. 3,071,961 patented Jan. 8, 1963 by J. J. Heigl et al provided an automatic viscometer. In the patented device, a system of light sources, each having a corresponding photodetector mounted opposite a light source, was employed for activating electronic equipment in order electronically and accurately to determine the length of time between the passage of the oil meniscus through a first paired light beam-photodetector arrangement, and then through a second paired light beam-photodetector arrangement.
U.S. Pat. No. 3,074,266 patented Jan. 22, 1963 to L. Sadler et al provided an automatic viscosity measurement device in which a float device was used which was responsive to the liquid level in the receiver for the discharge of liquid from a container, to measure and provide a direct reading of the time which elapsed for the rise of the liquid from a first level to a second level in the receiver.
U.S. Pat. No. 3,286,511 patented Nov. 22, 1966 by J. Hankness provided a viscosity measurement device in which a timer was connected to a pair of spaced-apart electrodes in a column through which liquid fell. The timer electrically registered the time interval for the forward end of the liquid stream to transverse the distance between the electrodes.
U.S. Pat. No. 3,604,247 patented Sept. 14, 1971 by P. Gramain et al provided an automatic viscosity meter including a vertical tube in which the liquid whose viscosity was to be measured flowed. The viscosity measurement was obtained by meansuring the time taken by a given volume of liquid to flow between two points. The reading of the passage of three miniscus past these two points was made automatically by using luminous sources and a single receiving element.
U.S. Pat. No. 3,713,328 patented Jan. 30, 1973 by Aritami provided an apparatus for the automatic measurement of viscosity. The timing means was activated by photoelectric devices consisting of pairs of photoelectric cells and light sources in pairs at the upper and lower timing marks of a timing bulb.
U.S. Pat. No. 3,908,441 patented Sept. 30, 1975 by J. M. Virloget provided a device for detaching the level of liquid in a transparent tube, for measuring the viscosity thereof. A radiation source was placed facing a region of the periphery of the tube. A photocell was placed facing a second zone of the tube periphery to receive radiation totally reflected from the internal face of the tube which was wetted by the liquid.